Because "normal" players will get upset, so it's bad for your business.
The same thing happens in sports betting, where retail punters absolutely hate if someone places a bet online during a game exactly after a goal was scored, but before the odds move. So even sports betting exchanges like Betfair forbid this kind of arbitrage and void it. Not because they really care, but because it annoys the other players.
While I don't understand what "retail punters" refers to, how does someone else's bet affect mine? I can't think of any scenario where I'd care once my bet was placed
The same thing happens in sports betting, where retail punters absolutely hate if someone places a bet online during a game exactly after a goal was scored, but before the odds move. So even sports betting exchanges like Betfair forbid this kind of arbitrage and void it. Not because they really care, but because it annoys the other players.